linux-kernel - Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

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Message-ID: <e5a25173-ebea-d856-ed25-45437769f17f@gmail.com>
Date:   Wed, 18 Nov 2020 11:57:44 +0100
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: mmap: fix fput in error path v2

Am 06.11.20 um 23:48 schrieb Andrew Morton:
> On Fri,  6 Nov 2020 12:48:05 +0100 "Christian König" <ckoenig.leichtzumerken@...il.com> wrote:
>
>> Patch "495c10cc1c0c CHROMIUM: dma-buf: restore args..."
>> adds a workaround for a bug in mmap_region.
>>
>> As the comment states ->mmap() callback can change
>> vma->vm_file and so we might call fput() on the wrong file.
>>
>> Revert the workaround and proper fix this in mmap_region.
>>
> Seems correct, best I can tell.  Presumably all ->mmap() instances will
> correctly fput() to original file* if they're rewriting vma->vm_file.

Yes, exactly.

Patch #2 provides a helper to make sure that everybody gets the 
get_file()/fput() correctly while updating vma->vm_file.

Can I add your acked-by to the patches and push them upstream through 
drm-misc-next?

Thanks,
Christian.